madcat-os (binary: madcat)

MADCAT MCP server and command line in Python. The installed binary is madcat; one package, three faces:

• madcat mcp serve — MCP over stdio (default) or Streamable HTTP at /mcp
• madcat mcp list / mcp call <tool> '<json>' — drive the tool registry from the shell
• madcat status — effective config and tool count
• madcat claude hooks pre-tool inject_session_id / session-start welcome — Claude Code hooks

Functionality is being moved here from the Rust madcat binary; command shapes match it.

Quick start

uv sync
uv run madcat status
uv run madcat mcp list
uv run madcat mcp call server_info
uv run madcat mcp serve --transport http --token t --bind 127.0.0.1:4197

Then POST an initialize to http://127.0.0.1:4197/mcp with Authorization: Bearer t and Accept: application/json, text/event-stream; reuse the returned mcp-session-id.

Claude Code

stdio:

{ "mcpServers": { "madcat": { "command": "uv", "args": ["run", "--directory", "/path/to/madcat-os", "madcat", "mcp", "serve"] } } }

http:

{ "mcpServers": { "madcat": { "type": "http", "url": "http://127.0.0.1:4097/mcp",
  "headers": { "Authorization": "Bearer ${MADCAT_MCP_TOKEN}" } } } }

Hooks, in ~/.claude/settings.json (event JSON on stdin, hook output on stdout, always exit 0):

"hooks": {
  "PreToolUse": [ { "matcher": "", "hooks": [
    { "type": "command", "command": "madcat claude hooks pre-tool inject_session_id", "timeout": 5 } ] } ],
  "SessionStart": [ { "hooks": [
    { "type": "command", "command": "madcat claude hooks session-start welcome", "timeout": 5 } ] } ] }

inject_session_id records the session in ~/.claude/current-session-id and current-session.json (MADCAT_CLAUDE_STATE_DIR, [claude].state_dir) and adds session_id to madcat tool calls (--server / MADCAT_CLAUDE_MCP_SERVER when the tool name does not identify madcat). welcome prints the boot prompt for the active persona cart (~/.local/share/madcat/tts-state.toml → ~/.config/madcat/carts/<tag>.toml); MADCAT_CLAUDE_WELCOME, [claude].welcome or $CLAUDE_PLUGIN_DATA/welcome.md replaces it.

Configuration

Environment, prefix MADCAT_MCP_ (or a .env file): HOST (127.0.0.1), PORT (4097), TOKEN, LOG_LEVEL. --bind and --token on mcp serve override.

Adding a tool

Create src/madcat_os/tools/<module>.py with register(mcp: MCPServer) and @mcp.tool() handlers (docstring per tool, type hints per argument), then add <module>.register to MODULES in src/madcat_os/tools/__init__.py. Human output goes to stderr; stdout is the stdio wire.

Layout

src/madcat_os/
  cli.py        Typer app: status, mcp list|call|serve
  server.py     build_server(), HTTP app with bearer auth + /health, stdio/http runners
  config.py     Settings (pydantic-settings); hook/cart getters over ~/.config/madcat/config.toml
  claude_hooks.py  Claude Code PreToolUse / SessionStart handlers
  cart.py       persona carts: tts-state.toml and carts/*.toml
  tools/        registry; one module per tool family
tests/
justfile